Monarchs & Bt corn issue update

Paul Cherubini paulcher at
Thu Jun 17 19:07:04 EDT 1999

Monarch Butterfly Researchers Urge Caution in Over-Interpreting Results

Academic Researchers and Industry Associations Agree Reports On Bt Crop Impact on
Monarch Butterflies Overblown

WASHINGTON, June 10 /PRNewswire/ -- Several academic experts have urged caution
when interpreting the results of a preliminary laboratory study at Cornell University on
the effect of Btcorn pollen on the Monarch   butterfly that was published as a letter in the
journal Nature (5/20/99).

These university researchers stressed that the monarch study did not represent natural
conditions and that extensive environmental research has confirmed the safety of Bt corn
on non-target insects, such as the ladybird beetle, honeybee and the green lacewing, in
the natural environment.

Dr. John Losey, the Cornell University entomology professor who conducted the
research said, ``Our study was conducted in the laboratory and, while it raises an
important issue, it would be inappropriate to draw any conclusions about the risk to
monarch populations in the field based solely on these initial results.''

In a response letter published in Nature (6/3/99), Dr. John Beringer, professor at the
University of Bristol's School of Biological Science in the United Kingdom and chairman
of the U.K. Advisory Committee on Releases to the Environment, wrote, ``There is a
need for scientific rigour in the presentation of the information to ensure that it is not
misrepresented ... preliminary observations should not be over-interpreted.''

``We want to make sure that the monarch is protected, and we want to verify the belief of
numerous scientists that Bt pollen is not putting the monarchs at significant risk,'' said
Dr. L. Val Giddings, vice president for food and agriculture, Biotechnology Industry
Organization (BIO).

Factors in field reduce likelihood of monarch exposure to corn pollen
By design, the Cornell researchers did not match the conditions that would be present in a
natural setting. In the laboratory, the caterpillars were given no choice but to feed on one
treatment, in this case leaves dusted with corn pollen. In the field, the caterpillars may
move about and may avoid ingesting pollen.

Under natural conditions, monarch larvae feed primarily on milkweed. Most researchers
consider it likely that most milkweed does not grow close enough to corn fields to be
exposed to significant amounts of corn pollen. According to an Iowa State University
study by Laura Hansen and Dr. John Obrycki, the majority of corn pollen stays within
the cornfield in a natural setting. The Iowa State study found that pollen density decreases
by 70 percent at the edge of a cornfield, and by 90 percent three meters away from the
edge of the cornfield.

Further, the majority of monarch larvae feed on milkweed when corn pollen is not
present. Corn plants produce or ``shed'' pollen for a short period of time (typically most
pollen is produced in a given field over a 5-10 day period.) Based on known migration
behavior, even in those regions in which corn and monarchs co-habitate, only a small
portion of the monarch population will be present when corn is shedding pollen.

For these reasons -- the location of milkweed outside the range of most pollen drift, and
minimal overlap between monarch feeding and pollen shedding -- it is likely that the vast
majority of monarch larvae throughout their range over a growing season are never
exposed to corn pollen in nature at all.

Bt Corn Benefits Non-target Insects

The Bt corn crops that are currently on the market were developed to control the European
Corn Borer. Prior to the introduction of Bt corn, farmers controlled European Corn Borer
with conventional insecticide sprays that are toxic to monarch butterfly larvae and other
desirable, non-target species. By reducing the use of these insecticides, Bt corn reduces
the potential to harm non-target species, and reduces impacts of agricultural inputs on the
environment in general.

``I still think the proven benefits of Bt corn outweigh the potential risks,'' stated Dr.
Losey. ``We can't forget that Bt corn and other transgenic crops have a huge potential for
reducing pesticide use and increasing yields.''

Dr. Chris DiFonzo, Michigan State University Field Crops Entomologist & Pesticide
Education Coordinator, said ``Bt corn is a much safer method of pest management, and
has less detrimental impact on all aspects of the environment -- monarchs included -- than
the use of broad-spectrum insecticides.''

``When you consider the monarch butterflies in context with the widely recognized
benefits of Bt crops, it's clear that trends in agriculture will only help the monarchs and
the environment overall,'' said BIO's Val Giddings. ``For example, Bt crops preserve
beneficial insects that prey on harmful insect pests, thus limiting the need for additional
insecticide sprays. Growers planting Bt crops have dramatically reduced the damage done
by harmful pests and have reduced handling and exposure of insecticides on the farm.''

``As conservation groups have noted, the primary threat to the monarch butterfly is the
loss of crucial winter habitat in southern California and central Mexico,'' Giddings
added. ``Other threats come from habitat degradation along butterfly migratory routes,
pesticides, and other human activities. It's not an exaggeration to say more monarchs
succumb to high-velocity collisions with car windshields than ever encounter corn

In addition to the extensive number of field studies that have been conducted to determine
the effect of Bt crops on beneficial insects, BIO and the American Crop Protection
Association are working along with industry partners to address and evaluate these issues
further. The available information strongly supports the advantages of Bt crops on
beneficial insect population relative to the use of insecticides.

For further information on this subject, contact the following independent experts:

              Warren Stevens, Ph.D.
              Missouri Botanical Garden
              4344 Shaw Blvd, St Louis, MO 63110-2291
              (314) 577-5103

              Albert Tenuta, Ph.D.
              Pest Management Specialist and Plant Pathologist
              Ontario Ministry of Agriculture, Food, and Rural Affairs
              Ridgetown Campus, University of Guelph
              Ridgetown, Ontario
              (519) 674-1617

              John Foster, Ph.D.
              Professor of Entomology
              University of Nebraska
              Lincoln, NE
              (402) 472-8686

              Marlin Rice, Ph.D.
              Professor of Entomology
              Iowa State University
              Ames, IA
              (515) 294-1101

              John Wedberg, Ph.D.
              Professor of Entomology
              Dept of Entomology
              University of Wisconsin
              Madison, WI
              (608) 262-1696

              Chris DiFonzo, Ph.D.
              Field Crops Entomologist
              (517) 353-5328

              Pat Bolin, Ph.D.
              (517) 353-3274
              Vegetable Integrator, IPM Program
              Michigan State University, Extension Service

              Galen Dively, Ph.D.
              Professor of Entomology
              University of Maryland
              4112 Plant Science Building
              College Park, MD 20742
              (301) 405-3913

              John Losey, Ph.D.
              Asst. Professor of Entomology
              Cornell University
              (607) 255-7376

              Riley Foster, Ph.D.
              Plant Pesticide Specialist
              University of Illinois
              (217) 367-5303

              John J. Obrycki, Ph.D.
              Professor of Entomology
              Iowa State University
              (515) 294-8622

              Department of Crop Science
              University of Illinois
              Urbana, IL
              (217) 333-6652
              Web site:

              Sarah Hake, Ph.D.
              Director, Plant Gene Expression Center
              U.S. Department of Agriculture
              Albany California
              (510) 559-5907

              Nina Fedoroff, Ph.D.
              Willaman Professor of Life Sciences
              University of Pennsylvania
              (814) 863-4576

              Terry Franel, Senior Economist
              American Farm Bureau Federation
              (202) 484-3600

              Jeffrey Barach, Ph.D.,
              Vice President, Special Projects
              National Food Processors Association
              (202) 639-5900

              Dave Schmidt, Vice President, Food Safety
              International Food Information Council
              Washington, DC
              (202) 296-6540

              L. Val Giddings, Ph.D.,
              Vice President, Food & Agriculture
              Biotechnology Industry Organization
              Washington, DC
              (202) 857-0244

              Allan Noe, Vice President
              American Crop Protection Assn.
              (202) 296-1585

              National Corn Growers Association
              St. Louis, MO
              (314) 275-9915

SOURCE: Biotechnology Industry Organization

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